Radioactive stent structures

Abstract

Methods and apparatuses for irradiating stent structures that are selectively collapsible or reducible along their longitudinal axis to reduce the total length thereof are described. Providing a collapsible stent structure reduces the effective surface area which must be exposed to the radiation beam, thereby reducing the time required for the irradiation process. Stent structures suitable for irradiation using the method and apparatus are also described.

We claim:  
     
       1. An apparatus for irradiating a stent structure to produce a radioactive stent structure comprising: 
       first and second plunger components, a plunger component support assembly for supporting said plunger components in opposed facing relation, at least one of said plunger components being movably mounted to said support assembly so as to be longitudinally displaceable towards the other of said plunger components to selectively capture a longitudinally collapsible stent structure therebetween; and  
       means for producing a radiation beam directed at least at an area disposed between said plunger components so as to irradiate a stent structure disposed between said plunger components.  
     
     
       2. The apparatus of claim  1 , wherein said support assembly comprises a housing defining an interior hollow chamber for receiving a stent structure to be irradiated, said at least one plunger component being movably mounted to a respective longitudinal end of said housing. 
     
     
       3. The apparatus of claim  2 , further comprising a central mandril extending along the longitudinal axis of said housing, said plungers being mounted in telescoping, surrounding relation to said central mandril. 
     
     
       4. The apparatus of claim  2 , further comprising means for controlling a temperature of said chamber of said housing. 
     
     
       5. The apparatus of claim  1 , further comprising a stent delivery system including a shaft on which the stent structure is received and a sheath disposed coaxially to said shaft and sized to receive the stent therewithin. 
     
     
       6. The apparatus of claim  5 , further comprising a receiver having a flared distal end and sized so as to be selectively disposed in surrounding relation to said sheath. 
     
     
       7. The apparatus of claim  5 , wherein said shaft has an enlarged distal end for selectively engaging said stent structure to displace the same proximally into the sheath. 
     
     
       8. The apparatus of claim  1 , wherein a distal end of one of said plungers has a transverse diameter larger than a transverse diameter of a distal end of the other of said plungers. 
     
     
       9. The apparatus of claim  1 , in combination with a longitudinally collapsible stent structure disposed between said plunger components. 
     
     
       10. The apparatus of claim  9 , wherein said stent structure is formed at least in part from a shape memory metal. 
     
     
       11. The apparatus of claim  9 , wherein said stent structure is formed at least in part from a material selected from the group consisting of tantalum, gold, stainless steel, nitinol and rhenium. 
     
     
       12. The apparatus of claim  9 , wherein the stent structure is constructed and arranged to telescopingly collapse from at least one end thereof. 
     
     
       13. The apparatus of claim  9 , wherein the stent structure comprises first and second circumferential ring structures disposed at each longitudinal end thereof and at least two stay elements extending therebetween to define a main body thereof, each said stay element being selectively foldable whereby said circumferential rings are selectively disposed adjacent each other thereby reducing an overall length of the stent structure. 
     
     
       14. The apparatus of claim  9 , wherein said stent structure is porous and/or has apertures defined therethrough. 
     
     
       15. The apparatus of claim  9 , wherein said stent structure is formed from a mesh material. 
     
     
       16. The apparatus of claim  9 , wherein said stent structure is formed from nitinol whereby said stent can be substantially longitudinally collapsed and upon removal of a compression force returned to substantially an original configuration thereof. 
     
     
       17. A method for irradiating a stent structure to produce a radioactive stent structure comprising: 
       providing an apparatus comprising first and second plunger components; a plunger component support assembly for supporting said plunger components in opposed facing relation; at least one of said plunger components being movably mounted to said support assembly so as to be longitudinally displaceable towards the other of said plunger components to selectively capture a longitudinally collapsible stent structure therebetween;  
       disposing a stent structure between said plunger components;  
       displacing at least one of said plunger components toward the other so that said stent structure is engaged and held therebetween;  
       producing a radiation beam and directing said beam toward said stent structure disposed between said plunger components; and  
       rotating said plunger components about a longitudinal axis thereof and/or moving said plunger components longitudinally so as to irradiate at least a portion of said stent structure.  
     
     
       18. The method of claim  17 , further comprising longitudinally collapsing said stent structure between said plunger components during said displacing step. 
     
     
       19. The method of claim  17 , wherein said providing step comprises providing a support assembly that includes a housing defining an interior hollow chamber for receiving the stent structure to be irradiated, said at least one plunger component being movably mounted to a respective longitudinal end of said housing. 
     
     
       20. The method of claim  19 , further comprising controlling a temperature of an interior of said chamber of said housing. 
     
     
       21. The method of claim  17 , further comprising providing a stent delivery system including a shaft on which the stent structure is received and a sheath disposed coaxially to said shaft and sized to receive the stent therewithin, and wherein said disposing step comprises advancing said stent delivery system through a passage defined in one of said plunger components, retracting said sheath, and radially expanding said stent structure. 
     
     
       22. The method of claim  19 , wherein said housing is translated longitudinally and/or rotated relative to the radiation beam with said plunger components.